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Digital delusion: A lesson from not-so-long ago

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When the nationalised railway was split up in 1994, former British Rail engineers now working for Railtrack faced an interesting time. While railway engineering talent had, up to then, been essentially home grown, Railtrack brought an influx of engineers from other safety-critical industries such as nuclear, oil and aerospace who did not necessarily understand the complexities of railway engineering and operations.

This was not necessarily a bad thing, as it did bring some worthwhile new ideas that the newly privatised railway could adopt, helped by the removal of the Treasury-imposed constraint of BR’s external financing limit.

For example, in BR days, painting the Forth Bridge was the never-ending job of painting on top of many old layers. Railtrack’s approach was to take the entire structure back to bare metal and apply a surface treatment that had been developed for use on North Sea oil rigs.

Yet BR’s engineers were right to be concerned, as it became apparent that Railtrack, as a procurement organisation, did not have the required engineering focus – an approach that would eventually destroy the company.

A cunning plan

One of the seeds of Railtrack’s demise was sown in a 1994 WCML (West Coast main line) feasibility study specifying its upgrade at a cost of £1.4 billion (all estimates in this article are current prices). In this report, American consultants Booz Allen & Hamilton proposed a way of replacing life-expired signalling equipment at low cost whilst offering substantial operational cost savings.

Their solution was moving block transmission-based train control (TBTC), equivalent to today’s ERTMS Level 3 in that it did not require track circuits or axle counters. This was to be operational on the entire WCML by 2004.

With the movement authority and permitted speed continuously displayed in cab, it offered automatic train protection without any lineside signals. A major advantage was that its “installation and commissioning can be carried out with minimal disruption to the existing signalling and train services” as this would not disturb the complex trackside signalling installations. Furthermore, the report advised that TBTC would avoid the need to replace life-expired track signalling equipment as it only required minimal train control infrastructure.

These benefits would not apply at “signalling islands”, where conventional signalling would be provided for non-WCML services crossing the route. Elsewhere, all trains would need in-cab equipment, requiring 1,800 cabs to be so fitted.

The report did not say much about the required digital radio system, other than that it was to make maximum use of commercial equipment and be developed in parallel with other European railways. Placement of radio equipment was to be the responsibility of the successful contractor.

With headways only constrained by train braking, TBTC offered capacity benefits. It also offered train speeds above 200km/h. The entire route was to have one control centre, which would eliminate the need for the 350 signallers who had anyway been on strike that year.

TBTC as shown in 1994 WMCL feasibility study.
TBTC as shown in 1994 WMCL feasibility study.

Only one snag

The only problem was that TBTC did not exist. Indeed, it has still yet to be implemented on a mixed traffic railway.

The report acknowledged the risks of developing and implementing this new system but considered that these could be mitigated through good management. There was no reference to a functional specification or delivery plan for this new technology.

Railtrack announced their WCML plan in March 1995. The then Transport Minister John Watts announced that its “most inspirational element is the proposed new signalling and control system.” One MP pointed out that it has not been proven anywhere. Watts responded that it was not new territory and very much in line with the proposed technical standards for the European train control system.

Yet, at about the same time, the EU published a report showing that ERTMS Level 3 was still a long-term prospect. Although this report recommended full-scale ERTMS tests on the European high-speed train network, these did not include Level 3, in part because there was, and still is, no proven technical solution for monitoring train integrity.

ERTMS level 3 as shown in a recent RDG presentation.
ERTMS level 3 as shown in a recent RDG presentation.

Acceptance of the unknown

How could a company have put such faith in implementing the untried TBTC system on a busy mixed traffic railway without heeding the European view or concerns expressed in the UK? For example, the House of Commons transport committee had warned: “Reliance on an as-yet unproven train control system to underpin the financial case for investment may lead to unacceptable delays in upgrading the nation’s principal intercity route.”

Other people had reservations too. John Welsby, then chairman of British Rail, told the Guardian newspaper: “I did have grave concerns about the attempt to integrate a type of technology that had no testing in real, active life in what, in fact, was the most complex railway in the country.” In addition, Chris Green, who was to head Virgin trains, considered: “It was a wish list. To put that wish list on Europe’s third busiest railway really was outrageous.”

It seems surprising that Railtrack’s senior engineers accepted the TBTC proposal. However, there were relatively few of them (Railtrack had no engineering department on the floor plan at its head office) and those from outside industry had little signalling experience.

Perhaps one reason for accepting TBTC was that it was about to become a reality on the Jubilee line extension then under construction. However, when it opened in 1999, it did so with conventional signalling due to “technical difficulties” with the TBTC system. The Jubilee line was eventually converted to ATO with moving block signalling in 2011.

Table from 1999 Nichols report compared Metro and WCML to show how different factors affect capacity, journey time and train delay.
Table from 1999 Nichols report compared Metro and WCML to show how different factors affect capacity, journey time and train delay.

Within Railtrack, there was huge pressure to adopt TBTC because it slashed costs and was the key to delivering the WCML upgrade. As a private-sector newcomer, Railtrack wanted to show itself as an innovative, smart company with a bold solution. This was well received by the city. By 1998, just over two years after its stock exchange flotation, its shares had soared from £3.80 to £17.68.

In 1996 Railtrack awarded two separate TBTC development contracts to GEC Alsthom Signalling (now Alstom) and Transig (a consortium of Adtranz and Westinghouse). Alstom began the design phase in 1999, under a second contract. Yet, by then, Railtrack had already commissioned the Nichols Group to report on the WCML programme, which was running into cost and time problems with track and structures work also well behind schedule.

The 1999 Nichols report concluded that there was only a five per cent chance of TBTC being operational by the 2005 target date and that the cost and time to fit TBTC cab equipment had been underestimated. So, in December 1999, the decision was taken to abandon TBTC. Instead, an ERTMS Level 2 signalling overlay would be provided between London and Crewe to allow 140mph operation.

Using extensive modelling, the report had also concluded that, whilst moving block offered significant capacity improvements for metro operations, the choice of signalling system has only a minimal impact on capacity on a mixed traffic railway as infrastructure is the major constraint. Hence the Nichols report also recommended infrastructure enhancements such as four-tracking the line through the Trent valley.

Freightliner train at Deansgate station.
Freightliner train at Deansgate station.


When the Virgin Rail Group won the WCML train franchise, it wanted more capacity and higher speeds. Virgin therefore agreed to contribute £600 million to an enhanced upgrade programme known as Passenger Upgrade 2 (PUG2) that would enable 140mph running by 2005. At the same time, it ordered a fleet of Pendolino tilting trains to run at this speed.

This deal was flawed as it did not involve any other WCML train operators. The initial proposal, that Virgin should have exclusive use of the fast tracks on the WCML’s four-track sections, was rejected by the Office of the Rail Regulator (ORR).

The Nichols report concluded that ERTMS Level 2 could deliver PUG2. However, as Level 2 requires track detection, this would require a significantly higher trackside signalling infrastructure renewal than originally envisaged. Partly as a result, the estimated cost of WCML upgrade rose to £7 billion.

Yet, even with this new approach, Nichols considered that there was only a 50 per cent confidence level that contractual commitments to Virgin could be met by May 2005.

Over the following years, as it became increasingly clear that PUG2 would not be delivered on time, Railtrack tried to renegotiate its commitments. Rail regulator Tom Winsor was not impressed and asked Railtrack’s CEO Gerald Corbett whether it was reasonable to expect contracts to be honoured. His response, that it was reasonable in the real world but, in many senses, the railway is not the real world, revealed the weakness of Railtrack’s position.

In 2001, Railtrack advised that it could not run Virgin’s Pendolinos at 140mph and so faced large penalty payments. At the same time, its finances were under severe pressure following the Hatfield crash.

An application for Government emergency funding was refused in October 2001 and Railtrack was put into administration. Shortly afterwards, the cost of the WCML upgrade was estimated to be £14.8 billion, ten times the 1994 estimate.

Virgin's Class 390 Pendolino trains. The 53 x 8-car units built between 2001 and 2004 were intended to run at 140 mph instead of their current 125 mph.
Virgin’s Class 390 Pendolino trains. The 53 x 8-car units built between 2001 and 2004 were intended to run at 140 mph instead of their current 125 mph.

After Railtrack

In June 2002, the Strategic Rail Authority (SRA) convened an industry-wide workshop which recommended that ERTMS Level 2 be removed from the West Coast programme and that its development work should be transferred to the SRA. As part of this work, it was announced in 2003 that, for trial purposes, the 217-kilometre single track from Shrewsbury to Aberystwyth and Pwllheli would be the first route equipped with ERTMS Level 2. It was to be eight years before this route was fully commissioned in 2011.

Following the 1997 Southall and 1999 Ladbroke Grove crashes, it was recognised that some form of automatic train protection (ATP) was required. With the increasing realisation that using ERTMS to provide ATP was not achievable in the medium term, the Train Protection and Warning System (TPWS) was introduced as an interim solution. However, TPWS weakened the business case for ERTMS as it prevents about 80 per cent of the signals passed at danger (SPAD) incidents that ATP could avoid.

With the abolition of the SRA in 2004, the ERTMS programme passed to Network Rail, which released a report in 2005 showing that the business case for ERTMS Level 2 could only be made if it completely replaced life-expired signalling equipment (i.e. no lineside signals) and gave significant capacity benefits. For this reason, significant deployment of ERTMS would take some time. Thus, it was considered that the WCML would not see the benefits of ERTMS until 2038. However, one advantage of this long-term programme is that it would largely avoid retrofitting cab equipment on existing trains.

Estimated costs of WCML programme from 2006 National Audit Office report.
Estimated costs of WCML programme from 2006 National Audit Office report.

The digital railway

In 2012, Network Rail announced the next stage of the ERTMS programme as contracts were awarded to four suppliers to develop technical solutions and test them on a nine-kilometre single-line section of the Hertford loop. The intention was that it would first be deployed on the Great Western and East Coast Main Lines starting respectively in 2014 and 2018 (issue 117, July 2014).

By then, it was evident that railway investment was struggling to meet the unpredicted doubling of passenger traffic over the previous twenty years. This strengthened the case for ERTMS if it could deliver capacity improvement without the need to build new rail infrastructure.

The Digital Railway initiative was launched in 2014. It envisaged an accelerated roll-out of ERTMS, with the entire network fitted by 2029. This was to include provision for the moving blocks provided by ERTMS Level 3 which Network Rail’s publicity claimed could unlock up to 40 per cent more capacity. This programme was also to benefit passengers in other ways, for example on-train broadband, e-ticketing, dynamic pricing and better travel information.

It soon became evident that this programme was overambitious. Partly because of this, digital signalling was considered in a report by the House of Commons Transport Committee, published in October 2016, which concluded that:

  • Solving existing Rail Operating Centre (ROC) issues must come before meeting the timetable of Digital Railway;
  • Digital signalling is not just about ETCS Level 2 – Network Rail should pick the most effective intervention for each route and press ahead with Connected Driver Advisory Systems and Traffic Management solutions where these are cost-effective;
  • Network Rail’s Digital Railway business case should include a full cost/benefit analysis of all potential systems for each route;
  • Network Rail should be very cautious about how it uses the 40 per cent capacity improvement claim;
  • Projections based on ETCS Level 3 should only be considered valid when the Level 3 specification is ready for deployment – until then, Network Rail should not promise “moving block” signalling system in its publicity;
  • The Digital Railway programme cannot be delivered without a cross-industry approach;
  • Rail freight must not be forgotten.

Digital delivery today

The first passenger-carrying train using Automatic Train Operation over ETCS Level 2 train control operated on the Thameslink core route in March 2018 (issue 164, June 2018). Crossrail services will soon be operating under the control of ETCS Level 2 on its Heathrow spur and Communications-Based Train Control (CBTC) in the central core section.

Traffic Management systems are also being implemented. They are in partial or trial use in the Cardiff area and London to Bristol routes with systems at Romford and Three Bridges to go live soon.

These schemes are part of a refocused Digital Railway programme in tune with the Transport Committee’s recommendations (issue 147, January 2017). It is now much more of a cross-industry initiative, though funded and facilitated by Network Rail, and has held several worthwhile early contractor involvement workshops. Its dedicated website emphasises both a cross-industry approach and the need to select the most appropriate mix of digital technologies for each route.

The thousands of new trains currently on order will all be ETCS fitted or be delivered “ETCS ready” and the government has agreed to substantial funding for the digital signalling programme, including the fitment of ETCS equipment to freight locomotives. In addition, all resignalling schemes now must have passive provision for ETCS (issue 164, June 2018). The programme is also aligned to conventional signalling renewals.

Manchester Piccadilly's crowded Platforms 13 and 14.
Manchester Piccadilly’s crowded Platforms 13 and 14.

Lessons from the past

After various false and slow starts, there now seems to be a credible strategy to provide Britain’s mainline railway network with digital signalling. Yet lessons from the WCML saga remain relevant today. One of these, highlighted by the 1994 report’s superficial treatment of radio, is the need for a robust radio system with sufficient data capacity.

A further issue is the need to understand that capacity improvement needs more than just digital signalling. Capacity modelling for the 1999 Nichols report showed that, whilst signalling headway is important, the main constraint to capacity on mainline railways is infrastructure.

Unfortunately, the Digital Railway programme’s website doesn’t seem to accept this message and makes the misleading claim that “digital deployment on the Thameslink will allow 24 trains per hour to run”. The reality is that this 24tph is the result of both digital signalling AND infrastructure work such as the Bermondsey Dive-under, which removed at-grade conflicts.

It helps that Thameslink has only one type of train. Its 24tph throughput would be dramatically reduced if it had to carry an hourly mixed-freight train. This is the situation faced by Manchester’s Castlefield corridor, which now carries extra trains following the construction of the Ordsall Chord (issue 159, January 2018).

This project was intended to be part of the larger Northern Hub capacity improvement scheme which included the construction of two additional through platforms at Manchester Piccadilly to increase capacity through the corridor by easing the passage of its hourly freight train and the constraints of dwell times on its two through platforms due to serious overcrowding on the island platform.

These extra platforms were actively progressed to the point of submitting a Transport and Works Act Order in 2015. Since then, the project has stalled and the Ordsall Chord only carries two trains an hour. Various government ministers have refused to commit to the extra platforms. Instead, Chris Grayling has asked Network Rail to consider whether digital technology can deliver capacity enhancements on the Castlefield corridor. Yet, as with Thameslink, the required capacity improvements through this corridor require both digital signalling and infrastructure works.

The pragmatic, inclusive approach of the current digital railway programme addresses many of the issues from previous attempts to deliver digital railway signalling. Yet it seems that decision makers still need to understand that, although it offers many benefits, the digital railway is no silver bullet.


  • ATO: Automatic Train Operation
  • C-DAS: Connected Driver Advisory System
  • Digital Railway: The use of modern digital technologies for train control and traffic management. Until recently, Network Rail used this term to mean any digital technology that could improve the railway.
  • ERTMS: The European Railway Traffic Management System which has two basic components, ETCS and GSM-R
  • ETCS: The European Train Control System consisting of infrastructure and train-mounted equipment.
  • GSM-R: A railway radio system based on the GSM standard for voice and data communication
  • TBTC: Moving block Transmission Based Train Control as proposed by the WCML project in 1994, equivalent to ERTMS Level 3.
  • Traffic Management: A system that maximises network performance by regulating trains to minimise conflicts at stations and junctions.

Read more: Looking forward to InnoTrans 2018


David Shirres BSc CEng MIMechE DEM
David Shirres BSc CEng MIMechE DEMhttp://therailengineer.com

Rolling stock, depots, Scottish and Russian railways

David Shirres joined British Rail in 1968 as a scholarship student and graduated in Mechanical Engineering from Sussex University. He has also been awarded a Diploma in Engineering Management by the Institution of Mechanical Engineers.

His roles in British Rail included Maintenance Assistant at Slade Green, Depot Engineer at Haymarket, Scottish DM&EE Training Engineer and ScotRail Safety Systems Manager.

In 1975, he took a three-year break as a volunteer to manage an irrigation project in Bangladesh.

He retired from Network Rail in 2009 after a 37-year railway career. At that time, he was working on the Airdrie to Bathgate project in a role that included the management of utilities and consents. Prior to that, his roles in the privatised railway included various quality, safety and environmental management posts.

David was appointed Editor of Rail Engineer in January 2017 and, since 2010, has written many articles for the magazine on a wide variety of topics including events in Scotland, rail innovation and Russian Railways. In 2013, the latter gave him an award for being its international journalist of the year.

He is also an active member of the IMechE’s Railway Division, having been Chair and Secretary of its Scottish Centre.



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